Sizing paper and product



United States I 1 SIZING PAPER AND PRODUCT Spencer H. Watkins, Wilmington, Del., assignor to Hercules Powder Company, Wilmington, DeL, a corporation of Delaware No Drawing. Application September 14, 1956 Serial No. 609,802

6 Claims. (CI. 92-21) This invention relates to improvements in the sizing of paper and more particularly to improvements in the engine sizing of paper with rosin sizes derived from tall oil rosin.

Tall oil rosin is derived from crude tall oil by treating the same to effect a separation of the resin acid and fatty acid components. Many processes for effecting this separation are known. One of the more elfective means is fractional distillation of crude tall oil at reduced pressure to obtain resin and fatty acids fractions, one being contaminated with as little as 3% or less of the other. A commercially available tall oil rosin competitive with gum and wood rosin is obtained by this method. Other methods involve 1) the fractional esterification of the fatty acids with polyhydric alcohols followed by the distillation of the resin acids, (2) total esterification of the tall oil followed by fractional saponification of the fatty acid esters followed by extraction, and (3) fractional precipitation of the resin acids out of acetone solution of the tall oil followed by decomposition of the resin acid salts with mineral acid.

Tall oil rosin may be converted into size in the usual manner by melting the rosin, adding sufiicient water and alkali, such as caustic soda, soda ash and the like, to give the desired total solids and free rosin, and stirring until a smooth paste is obtained. The resulting size may then be utilized for sizing in the conventional manner, namely, by mixing a dilute aqueous dispersion of the size with a suspension of paper pulp and then precipitating the rosin on the paper fibers by adding to the suspension 2, small quantity of aluminum sulfate (known as alum in the papermakers art). The dispersed tall oil rosin may be added in varying amounts, depending upon the result desired, but is usually added in amounts between about and about 4% based on the weight of dry pulp being treated. The amount of alum added will vary be- 2,872,315 Patented Feb. 3, 1959 dispersion, is added to a dilute aqueous suspension of pulp, such as in the beater of a papermaking machine, in an amount sufficient to supply from about A to about 4% of rosin based on the weight of dry pulp used. The rosin is then fixed to the pulp fibers by adding a small amount, i. e., from about /2 to about 5% based on the weight of dry pulp, of aluminum sulfate, following which the pulp is formed into paper in the conventional manner.

Having described the invention generally, the following examples are presentedin illustration but not in limitation of the invention. All parts and percentages tween about /z%' and about 5% but will usually be about 1% by weight of the dry pulp.

One of the objects of this invention is to provide a method of improving the sizing efilciency of tall oil rosin size dispersions such as those described above.

A further object of the invention is to provide a sizing adjunct which, when employed in combination with tall oil rosin in the engine sizing of pulp suspensions, not only provides a considerably higher degree of sizing than an equivalent amount of tall oil rosin alone but also permits equivalent sizing with much lower rosin dosages.

In accordance with the invention, these and other objects are attained if the tall oil rosin size compositions, utilized in sizing paper, contain from about 5% to about 20% by weight, based on the Weight of rosin, of a rosin acid dimer. It has been found that tall oil rosin sizing compositions so modified have greatly increased sizing efliciency which is indeed surprising since the rosin acid dimer itself has little, if any, sizing effect.

In carrying out the invention, a tall oil rosin size composition containing the indicated amount of rosin acid dimer, and preferably in the form of a dilute aqueous are by weight unless otherwise specified.

EXAMPLES 1-3 Paste sizes were prepared from tall oil rosin containing varying amounts of rosin acid dimer in the form of Dymerex, a product sold by the Hercules Powder Company. The sizes were cooked in the usual manner by melting the rosin, adding sufficient water and caustic to give the desired total solids and free rosin, and stirring until a smooth paste was obtained.

The sizes prepared as above, together with samples of Dymerex, were utilized in sizing paper in accordance with the following procedure. Bleached kraft pulp was beaten to a Shopper-Reigler freeness of 750110 cc. at 4.5% pulp consistency. This pulp was diluted to 2 /2% consistency with pH 7 water and the proper amount of size added as an aqueous dispersion containing 3% rosin size solids. Sufficient papermakers alum (about 2% based on the dry stock) was then added to lower the pH of the slurry to 4.5. The stock was then further diluted to 0.025% consistency and sheets of paper made in a Noble and Wood handsheet machine. The sheets were then pressed and dried and conditioned for 48 hours at 70 C., 50% relative humidity and tested for sizing. The results are set forth in the table below, the figures representing the degree of sizing reflecting an average of data obtained on two papermaking runs.

The Dymerex used in the examples is a pale colored thermoplastic resin sold by the Hercules Powder Company comprising approximately by weight of dimeric rosin acids and having the following physical properties:

Softening point:

Hercules drop method, C 152 ASTM ball and ring, C 139 Acid number 143 Saponification number:

Regular 145 Diethylene glycol 157 Unsaponifiable matter, percent 4 6.1 Color (U. S. D. A. rosin scale) M Gasoline insoluble Nil Molecular weight (in acetone) 502 Sulfur (Hercules lead oxide reactivity test) Negative Density at 20 C 1.069 Bromine number (KBr-KBrO method) 93 Hydrogen absorption, percent 0.51 Ash content, percent 0.005

3 Liebermann, scorch test- Positive Specific rotation 23.2'' Weight per U. S. gallon 8.91 Flash point (Cleveland open cup), F 487 The above examples clearly show that the efficiency of tall oil rosin as a sizing material is markedly increased when a rosin acid dimer is employed therewith. Thus, it is possible to obtain either a much larger amount of sizing with an equivalent amount of rosin, when the rosin acid dimer is employed, or the same degree of sizing may be obtained with considerably less rosin. This is of great advantage to the papermaker, particularly in those instances where it is desired to obtain a maximum amount of sizing at minimum cost.

The examples also" show that this increase in sizing efliciency is due to asynergis'tic effect and not to try inherent sizing characteristics of the rosin acid dimer itself since it is clear from Example 3 that the dimer has no appreciable sizing efiect.

The amount of rosin acid dimer contemplated for use herein may vary from about 5% to about 20% by weight based on the weight of rosin. Amounts below 5% do not give any effective increase in sizing eificiency while amounts above about 20% add nothing to the sizing efiiciency'and, in fact, cause a decrease in sizing efficiency as the percentage of dimer is increased.

In the preparation of the rosin size compositions utilized in the process of the present invention, the rosin acid dimer may be added to the tall oil rosin and the rosin then converted into size in the usual manner. Alternatively, the rosin acid dimer may be added during or after preparation of the size or prepared in situ by treating the tall oil rosin to form therein the amount of rosin acid dimer required to give the desired increase in sizing efficiency.

Rosin acid dimers suitable for use herein may be prepared by conventional methods well known to the prior art. These, in general, involve treating rosin with suitable polymerization catalyst, e. g., a strong acid such as sulfuric or phosphoric acid, an amphoteric metal halide such as aluminum chloride, zinc chloride, or boron trifluoride, an acid salt such as sodium acid sulfate, and so on. The rosins utilized may be ordinary gum, wood or tall oil rosin, specially refined and/or purified rosins and so on.

The advantages of the invention are realized when the rosin size compositions contemplated for use herein are prepared from tall oil rosin. While tall oil rosin varies somewhat depending on its derivation and method of recovery and purification, the following are typical properties of such a product prepared by fractional distillation at reduced pressures.

Acid number 168-172 Saponification number 172-178 Softening p'oint (ring and ball) 78-85 C. Resin acids 89.0-91.0 Fatty acids 1-3 Ultraviolet:

Total abietic-type acid 45-55 Dehydroabietic acid -20 Color (USDA rosin color scale) N-WG Specific rotation -5.0 to +5.0

In addition to rosin acid dimers, the tall oil rosinsize compositions, contemplated for use herein, may also contain adducts of rosin and materials such as maleic anhydride, fumaric acid, citraconic acid and the like.

It will thus be seen that the present invention provides increased sizing efficiency for tall oil rosin size compositions when employed in the sizing of paper in accordance with procedures conventionally used in the art. While preferred embodiments of the invention have been specifically described herein, the invention is not to be construed as limited thereby except as the same may be included in the following claims.

What I claim and desire to protect by Letters Patent is:

1. In the process of sizing paper with tall oil rosin size wherein the size is added to an aqueous suspension of pulp and the pulp then formed into a web of paper, the improvement which comprises incorporating with the tall oil rosin size from about 5% to about 20% by Weight, based on the weight of the tall oil rosin, of a rosin acid dimer.

2. In the process of sizing paper with tall oil rosin size wherein the size is added to an aqueous suspension of pulp and the pulp then formed into a Web of paper, the improvement which comprises incorporating with the tall oil rosin size from about 5% to about 20% by weight, based on the weight of the tall oil rosin, of a mixture of dimeric rosin acids.

3. The process of sizing paper which comprises adding to an aqueous suspension of paper pulp from about A to 4% of a tall oil rosin size containing from about 5% to about 20% by Weight, based on the weight of the tall oil rosin, or" a rosin acid dimer, beating the rosin dispersion into the pulp, admixing with the thus treated pulp from about /2% to about 5% of aluminum sulfate based on the weight of the dry pulp, and then forming the pulp into paper.

4. The process of sizing paper which comprises adding to an aqueous suspension of paper pulp a dilute aqueous dispersion of an at least partially neutralized mixture of tall oil rosin and rosin acid dimer, said aqueous dispersion containing from about 5% to about 20% of the rosin acid dimer based on the weight of the tall oil rosin and being added to the aqueous suspension of paper pulp in an amount sutficient to supply from about ,4, to 4% rosin based on the weight of dry pulp, admixing with the thus treated pulp from about /1 to about 5% of aluminum sulfate based on the weight of the dry pulp, and then forming the pulp into paper.

5. Paper sized with from about A to about 4% tall oil rosin, /2 to 5% aluminum sulfate based on the fiber, and from about 5 to about 20%, based on the weight of the tall oil rosin, of a rosin acid dimer.

6. Paper sized with from about A to about 4% tall oil rosin, /2 to 5% aluminum sulfate based on the fiber, and from about 5 to about 20%, based on the weight of the tall oil rosin, of a mixture of dimeric rosin acids.

References Cited in the file of this patent UNITED STATES PATENTS 1,929,115 Iohnstone Oct. 3, 1933 2,017,866 Morton Oct. 22, 1935 2,074,192 Schnorf Mar. 16, 1937 2,684,300 Wilson July 20, 1954 2,730,511 Floyd Jan. 10, 1956 2,771,464 Mastings et a1 Nov. 20, 1956 2,791,578 Drechsel et al May 7, 1957 OTHER REFERENCES Davis et al.: The Analyst 78, pp. 670-2; 1953; British magazine; abstracted in Chem. Abstr. 1954, vol. 48 pg, 1703d. V 

1. IN THE PROCESS OF SIZING PAPER WITH TALL OIL ROSIN SIZE WHEREIN THE SIZE IS ADDED TO AN AQUEOUS SUSPENSION OF PULP AND THE PULP THEN FORMED INTO A WEB OF PAPER, THE IMPROVEMENT WHICH COMPRISES INCORPORATING WITH THE TALL OIL ROSIN SIZE FROM ABOUT 5% TO ABOUT 20% BY WEIGHT, BASED ON THE WEIGHT OF THE OIL ROSIN, OF A ROSIN ACID DIMER. 